Ovarian Pathologies in the Buffalo

Ovarian dysfunction is common during the postpartum period [1] and is a significantly important clinical entity as this affects the ability of an animal to reproduce and produce milk. The ovaries and ovarian structures of buffaloes are inherently smaller compared to cows and seasonal ovarian hypofunction and ovarian pathologies limit the breeding value of this important species [2]. Ovarian abnormalities impair the development of ovarian follicles and corpus luteum and subsequently estrous cycle and pregnancy in buffaloes [3,4]. The overall incidence of ovarian pathologies in the buffalo varies from 8.58% to 48% [5-12]. Adult buffaloes are more likely to suffer from abnormalities of the ovaries compared to buffalo heifers [7] although one small abattoir study on Egyptian buffaloes recorded a higher incidence in buffalo heifers [8]. Many abattoir [7,13-21] and clinical studies [22-26] have identified some ovarian pathology in the bubaline species, however, their clinical description is still far from perfect. Clinical evaluations commonly utilize transrectal palpation as the means of differentiating various ovarian pathologies although its efficiency continues to be low even for the physiological structures that form on the ovarian surface periodically (follicles and corpora lutea) [27-29].

More recently hormone assays [30-32] and trans-rectal ultrasonography [33-39] have been utilized in identifying ovarian structures and reproductive dynamics in buffaloes, however; their use in identifying ovarian pathologies has been less documented. Ovarian hypofunction in the buffalo is strongly affected by seasonal changes [40] nutrition [41] and diseases such as trypanosomiasis [42] and should therefore be carefully evaluated. Ovarian pathologies have been sparsely classified for most domestic animals [43] and in the buffalo they are less frequently documented under clinical settings, probably because of the frequent slaughter of aged and sub fertile buffaloes [11] that probably suffer the most from pathological alterations in size, shape and function. In this chapter the author describes the ovarian pathologies in the buffalo. The classification of ovarian pathologies has been done under the following subheadings as mentioned recently [2]:

1.    Ovarian Developmental Anomalies
1.1. Ovarian Hypoplasia and Aplasia
1.2. Freemartin
1.3. Hermaphrodites
1.4. White Heifer Disease

2. Ovarian Inflammatory Conditions
2.1. Oophoritis and Perioophoritis
2.2. Ovarian Abscess
2.3. Ovaro-Bursal Adhesions
2.4. Ovarian Sclerosis

3. Ovarian Functional Disorders
3.1. Ovarian Hypofunction
3.2. Polyoogonia
3.3. Persistent Corpus Luteum
3.4. Ovulatory Disturbances
3.5. Ovarian Cysts
3.6. Paraovarian Cysts

4. Ovarian Neoplasms and Associated Conditions
4.1. Ovarian Neoplasms
4.2. Hematoma

1.        Ovarian Developmental Anomalies

Ovarian developmental anomalies are less frequent in the bubaline species and some of the anomalies have been described in clinical studies while others derive from studies carried out on abattoir material. Clinical descriptions for some conditions suffer from biased evaluations based on size dimensions of bubaline ovaries and not on actual detailed scientific analyses.

1.1. Ovarian Hypoplasia and Aplasia

The medical definition of ovarian hypoplasia is the incomplete or arrested development of ovarian tissue whereas aplasia is the complete absence of ovaries. Hypoplasia is similar to aplasia but less severe and both conditions are considered to be congenital. Ovarian hypoplasia associated with a deficiency of germ cells occurs infrequently in cattle [43]. This condition of the ovary is considered to be due to the failure of migration of primordial germ cells from the yolk sack to the developing gonad during the embryonic stage [44]. Thus the developing gonad becomes devoid of germinal epithelium which is the precursor of the follicular system. Both ovaries may be affected or sometimes only a single ovary or a part of the ovary may be affected. The ovary is small in size and is devoid of follicles or corpora lutea. In the Swedish Highland cattle breed, hypoplasia is determined to have been caused by a single recessive autosomal gene [44,45]. Ovarian hypoplasia has been described in many clinical and abattoir studies in buffaloes (Table 1) with visualization of dense stroma and anovular cords in histopathologic sections (Fig. 1) being considered hypoplasia in abattoir studies and smaller ovarian dimensions in clinical studies. The clinical descriptions, however, are far from perfect (many small sized ovaries may show follicle growth although the small follicles are not palpable (Fig. 2). Many clinicians often consider the smaller size of the bubaline ovaries to be hypoplasia, but this is inaccurate given that buffaloes have inherently smaller ovarian dimensions compared to cattle [46]. Clinicians must evaluate the ovaries by ultrasonography detecting follicular growth in normal although small sized ovaries (Fig. 3) and presumably the absence of any follicular growth as observed on sequential examinations at a definite body weight and age.
Sex chromosome abnormalities such as monosomy X was found to result in gonadal dysgenesis with poor development of both ovaries in buffaloes [47,48].

Figure 1. Microphotograph of hypoplastic ovary showing dense stroma and anovular cords H&E 100X.

Figure 2. Follicular growth evident in a cross section of a small-sized buffalo ovary.

Figure 3. Ultrasonographic image of a 1 cm-sized buffalo ovary. Small sized follicles are visible eliminating the possibility of this being a hypoplastic ovary.

Hypoplasia is considered to be inherited in cattle [53], however, similar descriptions are not available for the buffalo. It appears that true germ cell weakness as observed in Swedish cattle has not been observed in buffaloes.

1.2. Freemartin

A freemartin is an infertile female (born co-twin to a male) that is imperfectly developed and sterile probably due to the influence of the male hormones of the twin during development in the uterus [2]. The sex determining region deriving from the male masculinizes the ovarian primordial cells of the undifferentiated female fetus and induces the secretion of androgens [54]. Freemartinism is distinct form of intersexuality which arises as a result of vascular anastomosis of the heterozygous fetuses in multiple pregnancies [55]. In freemartins, the ovaries of the female fetus usually fail to develop, and remain small and rudimentary. The genital tract is underdeveloped but the vulva may be fairly normal with a prominent clitoris and large tuft of vulvar hair. The frequency is dependent on heterosexual twinning in the population. Around 85-92 % of the female co-siblings have been reported as sterile freemartins in cattle [56,57].

Freemartin was recorded in a Murrah buffalo [58]. Studies on 42 buffaloes with reproductive problems at maturity in Italy revealed 10 freemartins determined by cytogenetic evaluations. Of the eight females affected 6 showed normal body conformation, vagina and clitoris while 2 showed some male traits (tight pelvis). The two males were normal with only a reduced size of testicle in one animal [59]. In this study and another study [60] all the freemartin buffaloes were from single births which probably originated because of early death of the male co-twin. This makes it difficult to suspect the single born female being a freemartin [60]. In one study, sex chromosome chimerism was observed in triplets born to a Murrah buffalo [61]. Another study [62] evaluated heterosexual river buffalo quadruplets and found that the female calves born co-twins to males were not freemartin. Cytogenetic evaluations of 119 female and 13 male buffaloes with reproductive problems revealed that 18 females were freemartin and all freemartin females were sterile [48]. It appears that the general description used for defining freemartins in cattle is not applicable to bubaline species; freemartins seem to be uncommon in buffaloes.

1.3. Hermaphroditism

A hermaphrodite is an individual that has both male and female reproductive organs. A hermaphrodite animal has congenital anatomical variation that confuses the diagnosis of sex. True hermaphroditism is a bisexual manifestation in which both ovarian and testicular tissues are present. The occurrence of true hermaphroditism is extremely rare in buffaloes [2]. In pseudo-hermaphrodites, gonads of one sex only are evident with external genitalia and secondary sexual characteristics resembling those of the opposite sex. A male pseudohermaphrodite (genetic male with feminization of external genitalia) was reported in an Indian buffalo [63]. Similarly 4 clinical cases of male pseudohermaphroditism in buffaloes were also described [64].

1.4. White Heifer Disease

This inherited, congenital segmental aplasia of the tubular genitalia (paramesonephric duct), receives its name from the relatively high frequency in White Shorthorn heifers. However, it may occur in any breed of cattle. The aplasia can occur anywhere along the duct system but is most common in the cervical area. The remaining part of the uterine horn often gets filled up with secretions. A similar disease was also described in a Rathi heifer [65], buffalo specimens [63] and crossbred Jersey heifer [66]. The disease is associated with subfertility in a large number of animals of the herd and considered an inheritable disease in cattle [67]. A buffalo freemartin with adhesions on both ovaries and mucus accumulation in the right uterine horn cranial to the cervix was reported in Brazil [68]. A few cases of persistent hymen have been recorded in the buffalo [69,70] with expulsion of accumulated mucus on surgical excision of the persistent hymen [70], however, other features common to white heifer disease were not mentioned in these studies.

1.5. Diagnostic and Therapeutic Approaches

The diagnosis of most ovarian developmental anomalies requires specialized techniques. Hypoplasia in women is established on the basis of endocrinological evaluations and histological biopsy specimens [71]. Lagerlof and Settergren, [45] diagnosed hypoplasia in Swedish Highland cattle by transrectal palpation of small sized furrowed or spindle shaped ovaries and a lack of germ cells was observed on histologic sections. More recent studies have utilized PCR assays [44]. However, the diagnosis of hypoplasia in live animals continues to be difficult because of the poor clinical expression of this hereditary disorder. Studies on buffaloes evaluating the histologic evidence of poor presence of germ cells are not available.

Sonographic diagnosis of hypoplasia has been recently mentioned for cows [72], however, it is difficult to apply the technique clinically in buffaloes. Hypoplasia is difficult to diagnose clinically, the absence of secondary sexual characteristics is the only clinical sign in the presence of bilateral ovarian hypoplasia [71].

It has been mentioned that freemartin heifers can be readily diagnosed through the breeding history and clinical examination where the length of the vagina is found to be 1/3rd the normal length and a test tube can be inserted only up to a few centimeters deep into the vagina due to its under-development [54]. Cytogenetic evaluations are suggested for confirmation of the condition in infertile cows as freemartin is considered a chimera and some animals may not evidence the external features characteristic to freemartins [57]. The majority of freemartins are infertile and its karyotyping is XX/XY sex chromosome chimerism. Polymerase chain reactions are used to identify Y-chromosome DNA segments for the diagnosis [73] however, the high cost of such tests limits their routine clinical use. The clinical expression of freemartins (altered genitals) as observed in cattle is not common in the buffalo species and cytogenetic evaluation seems necessary. Evaluation of blood cell chimerism from 200 buffalo bulls revealed 3 young bulls with sex chromosome chimerism (XX/XY). The study concluded that compared to cattle, chimerism was uncommon in buffalo bulls [55]. However, the fertility of chimeric buffalo bulls is not affected. Studies on buffalo microsatellite markers evaluated and found that bovine sexing markers can also be used for evaluation of freemartin in buffalo [74].
Hermaphrodites are evident clinically whereas white heifer disease is usually confirmed in abattoir specimens.
The therapy for ovarian hypoplasia in cattle is not suggested as the condition is inherited. Since small ovarian dimensions appear to have been interpreted as hypoplasia, the suggested therapy in buffaloes is improved nutrition and management. The therapy of most other developmental anomalies is neither possible nor suggested [2]. In general, it is suggested to cull freemartin heifers.

2. Ovarian Inflammatory Conditions

2.1. Oophoritis and Perioophoritis

The inflammation of the ovaries and surrounding structures is known as oophoritis and perioophoritis. The most common pathological condition of the bovine ovary is perioophoritis [2,75] while oophoritis seems to be rare.
Perioophoritis and oophoritis were reported from abattoir studies on buffalo genitalia and their incidence varied from 0.3 % to 8.3 % [13,14,76-80]. A few of the more recent abattoir studies also described a similar incidence in buffaloes (Table 2).

The etiology of inflammatory conditions of the ovaries usually lies in the ovarian manipulations, although infections from the uterus and infectious diseases like tuberculosis and brucellosis might also be involved [89]. Severe bilateral inflammation causes sterility. In unilateral cases, however, the prognosis is guarded. Whenever the mesosalpinx or salpinx is involved in the inflammatory process, the situation is more serious. Trauma caused by improper manipulations during palpation, forced attempts to enucleate the corpus luteum or to manually rupture cystic ovaries, is the most common cause of oophoritis. In tuberculosis when the reproductive tract is affected, the ovaries are also involved. Suppurative oophoritis may follow severe metritis and perimetritis. A buffalo with tuberculosis is probably culled because it represents a serious zoonosis problem and therefore fertility is the least important thing to consider however more often such buffaloes are culled for fertility reasons due to poor diagnosis.

Perioophoritis is usually chronic and often localized and seen as red fibrous and serosal tags attached to the surface of the ovary especially in heifers (seen at necropsy). Granulomatous perioophoritis may occur in peritoneal tuberculosis and in setariasis which may appear as small reddish nodules or tags. These infective granulomas remain strictly localized on the surface of the ovary and do not penetrate its stroma [21]. Grossly the ovarian surface is shaggy and often encapsulated with adhesions which interfere with ovulation.

2.2. Ovarian Abscess

Rare incidence of ovarian abscesses (0.85 percent) was recorded in Berari (Nagpuri) buffaloes [84]. The abscess usually develops subsequently to the localization of the focus of infection following ovarian inflammatory disease. An ovarian abscess is silent clinically when smaller in size and can be diagnosed with precision only by transrectal ultrasonography [90]. A buffalo with large ovarian abscess may fail to show estrus when the condition is bilateral and such buffaloes may show pain on transrectal palpation of the ovaries.

2.3. Ovaro-Bursal Adhesions and Encapsulation

The condition results from adhesions between the mesosalpinx and mesovarium, often including the fimbriae and the ovary. The extent of the adhesions varies within specimens, showing fine web-like strands in the depth of the bursa which do not involve the oviduct, to instances of complete envelopment of the ovary in a closely applied fibrous bursa (Fig. 4). Intermediate cases show fibrous strands of varying thickness which connect the fimbriae or bursa to the ovary. The condition is uncommon in heifers but its incidence increases with the age of the buffalo. Trauma from rough handling of the ovary and bursa by rectal manipulation or clinical enucleation of the corpus luteum and descending infections are common causes of this condition.

Figure 4. Complete ovarobursal adhesion in buffalo genitalia (Photo Courtesy Prof. Azawi O.I., Department of Surgery and Theriogenology, College of Veterinary Medicine, University of Mosul, Mosul, Iraq).

Many evaluations on abattoir material revealed an incidence varying from 1.5%-18% [13-15,76,77,91-94] and a nearly similar incidence was recorded in recent studies (Table 2). Clinical evaluations, however, recorded an incidence of less than 3% [22,23,49] probably because of the difficulty in diagnosing this condition clinically since there are no clinical signs. In one clinical study on 31 repeat breeding buffaloes no ovarobursal adhesions were recorded [95].

The ovarobursal adhesion affects fertility mainly by interfering with tubal motility and leads to irregular returns to estrus. There is no satisfactory treatment for this condition. Some cases may be prevented by smooth handling of ovaries and preventing irrigation of uteri with large quantities of antiseptics. Use of proper suture material and asepsis during cesarean section might prevent some of the ovarobursal adhesions that may follow surgery [96].

2.4. Ovarian Sclerosis

Sclerosis means hardening or induration. Ovarian sclerosis appears to be a frequent gynecologic reason for which buffaloes are culled [83]. It is also one of the common ovarian abnormalities noticed in abattoir specimens (Table 2). Histopathologic evaluations revealed a thick tunica albuginea and dense stroma with fibrous bands (Fig. 5). The ovaries are usually very small and hard without any follicles. The etiology for ovarian sclerosis is poorly known. The pathogenesis of systemic sclerosis in human beings involves vascular, fibrotic, inflammatory, and immunologic processes [97] and probably similar mechanisms might be involved in buffaloes. Ovarian tuberculosis as recorded for cows [75] could be a possible reason for induration of ovaries. Severe debilitating diseases or inanition in buffaloes could also possibly be involved in this condition.

The incidence of the condition has been reported to vary between 1.69-11.4% in various studies in buffaloes (Table 2).

Figure 5. Microphotograph of a sclerosed buffalo ovary showing absence of surface epithelium, thick tunica albuginea and dense stroma with fibrous strands. H&E 200X.

2.5. Diagnostic and Therapeutic Approaches

Enlargement and hardening/thickening are the key diagnostic features for diagnosis of most ovarian inflammatory conditions including oophoritis and sclerosis [98]. Most ovarian inflammatory conditions are clinically silent in most domestic animals including the buffalo. The more severe type of ovarobursal adhesions can be diagnosed by transrectal palpation. In women, advanced diagnostic techniques such as ultrasonography [99], computed tomography [100], laparoscopy [101] and MRI [99] are routinely used in women with pelvic inflammatory disease, with pelvic pain as the most striking clinical sign. Ultrasonographic evaluations can detect ovarian abscess and to some extent ovarian sclerosis [90] in cows, however, similar descriptions are not available for the buffalo. The heterogeneous hypoechogenic specks of the abscess can be visualized within the ovarian boundary. Laparoscopic examination of buffalo ovaries has been mentioned [102-104], however, its use for detection of ovarian pathologies has not been described.

Therapeutic approaches suggested for ovarian inflammatory conditions in women include the administration of antibiotics [105] and surgical excision in acute conditions such as ovarian abscess which are life threatening [106]. However, similar approaches are less likely in most domestic animals including buffaloes due to financial considerations. Buffaloes with ovarobursal adhesions and sclerosis are more likely to be culled when diagnosed [83]. An ovarian abscess may sometimes regress or rupture spontaneously. If the abscess ruptures, the chances of adhesions forming are high and therefore this creates other problems that will also adversely affect fertility. Ovarian abscess might subsequently persist as sclerosis. Approaches for therapy of ovarian abscess can utilize the administration of broad spectrum antibiotics or trans-vaginal ultrasound guided aspiration of the contents. Such approaches are suggested only when the fertility of a precious animal is at stake.

3. Ovarian Functional Disorders

3.1. Ovarian Hypofunction

Subestrum or Silent Heat

Sub-estrum, popularly known as silent heat is a clinical condition in which in spite of the normal ovarian cycle, i.e. periodic follicular growth, ovulation and luteinization, overt estrus does not occur normally. Because behavioral signs of estrus are too weak, the animal in heat is missed and not inseminated or brought to the bull and the reproductive cycle is missed.

Possible causes include sub-optimal secretion of estradiol by mature follicles, abnormal ratio between estrogen and progesterone, and higher estrogen threshold for nervous excitation involved in the expression of estrus behavior [107]. A hereditary predisposition to the condition although not documented but might be possible. Silent heats are common during the post-pubertal period in heifers [107] and during summer months [108] and early postpartum period in adult lactating buffaloes [109]. In buffaloes, seasonal factors play a prominent role [110-112]. The smaller size of the follicles and a slower growth rate of follicles have been postulated to be one reason for sub estrus in buffaloes [113] and low levels of circulating hormones and biochemicals have been mentioned as another probable cause [114]. However, the etiology of subestrus in buffaloes continues to be poorly understood. The diagnosis is based on clinical examination. One clinical study [26] recorded an incidence 7.85% for sub-estrus in buffaloes.

Gestational Estrus

Estrus exhibited during pregnancy was often observed in both cows and buffaloes. Studies in cows revealed the incidence to range from 4.18 to 6.51% occurring once or multiple times at 112 days of gestation [117]. In buffaloes, 6.05% incidence of gestational estrus was reported at an average of 108≥12 days of gestation at IVRI, Izatnagar India [117] and 14.4% incidence was reported in the buffalo herd at the PAU, Ludhiana. Reproductive efficiency of such animals was above the herd average. Chauhan et al. [118] recorded a very high incidence of 20.3% among buffaloes in Punjab. Recent studies have shown that follicular growth and maturation continues during gestation in buffaloes [119]. Apparently a moderate decrease in progesterone levels during pregnancy leads to maturation of dominant follicle and increased estradiol production sufficient to result in overt estrus, but insufficient to terminate pregnancy. [120].

3.2. Polyoogonia

Polyoogonia is a condition in which each follicle which normally contains only one ovum may contain several ova without disturbing the function of genital organs. An incidence of 0.24% was recorded in a previous study in buffaloes [81]. This condition is almost never seen in a normal clinical setting, this is only seen under research conditions.

3.3. Persistent Corpus Luteum

A corpus luteum is considered persistent if the CL is palpable at two consecutive examinations at 10-12 days interval with no palpable change in size and consistency. A persistent corpus luteum in bovines is mostly associated with uterine pathology – pyometra or a macerated and mummified fetus. It may also be associated with an early embryonic death due to infections [121] or defective embryonic development, and it is often difficult to distinguish this with a cyclical CL unless and until two consecutive transrectal palpations at 10 days intervals are performed. Persistence of the CL is common during the postpartum period in buffalo due to uterine pathologies such as endometritis and pyometra [107,122].
In a few previous studies utilizing abattoir derived buffalo genitalia [13,14,22,23,77,91], the incidence of a persistent CL was calculated to vary between 0.19%-9.12%. A similar incidence was recorded in more recent studies on abattoir derived buffalo genitalia (Table 3).

3.4. Ovulatory Disturbances

Ovulatory disturbances include delayed ovulations and ovarian cysts.

Delayed Ovulation/Anovulation

Ovulation failures appear to be caused by the same endocrine malfunctions that result in the development of follicular cysts. Clinical diagnosis requires that the same follicle be detected in the same ovary upon at least two subsequent examinations, one at the peak of estrus and another between 24 and 36 hours later. Absence of CL in either met estrus or diestrus is a positive sign of anovulation.

Among Indian buffaloes 0.66 per cent ovulation failures were reported in Andhra Pradesh [22], 3.0 per cent in Jammu province [123], 4.0 per cent in Andhra Pradesh [23], 2.62 per cent in milk-shed areas and 15.09 per cent in repeat breeder buffaloes in Gujarat [124].

3.5. Ovarian Cysts

Ovarian cyst refers to a condition in which the ovarian follicular size of the ovary grows to more than 2.5 cm in diameter without ovulation [125] and is grouped as either follicular cyst or luteal cyst. The frequency of follicular cyst is higher than that of luteal cyst. The incidence of ovarian cysts in one study on buffalo was 2.7% [50]. In general buffaloes have a low incidence of ovarian cysts (Table 4). Unilateral or bilateral hemorrhagic cysts were recorded in previous studies on Egyptian buffaloes [126127,]. Buffaloes with ovarian cysts revealed significantly lower progesterone, T3 and T4 and significantly higher estradiol [127]. Bilateral ovarian cysts have been recorded in buffalo [128]. Biochemical evaluations of follicular fluid of follicular cysts revealed increased concentrations of nitric oxide, progesterone and cortisol and lower concentrations of ascorbic acid, insulin and glucose [129].
Histopathologic evaluation of follicular cysts revealed a thin or thick connective tissue around a degenerating layer of granulosa cells (Fig. 6) with excessive follicular fluids in buffaloes [130].

3.6. Paraovarian Cysts

Paraovarian cysts are remnants of the mesonephric ducts that are occasionally found around the ovary and fallopian tubes; they are attached to the broad ligaments of cows and buffaloes (Fig. 7). Tiny paraovarian cysts of a few millimeters in diameter are incidental findings in slaughtered buffaloes. They are of little significance in relation to fertility.

The cysts may vary in size from 1 to 5 cm in diameter and are usually round or oval in shape. They can be mistaken as a cystic ovary at transrectal palpation because of their closeness to the ovary. Previous studies in buffaloes recorded the incidence of paraovarian cysts varying from 0.43%-13.0% [79,84,92,94]. A nearly similar incidence was recorded in recent studies in buffaloes (Table 4).

Figure 6. Microphotograph showing the wall of a follicular ovarian cyst on the ovary of a buffalo. The granulosa layer is absent and the theca layer reveals luteinization. H&E 40X.

Figure 7. Multiple paraovarian cysts in the reproductive tract of a buffalo (Photo Courtesy Prof. Azawi O.I., Department of Surgery and Theriogenology, College of Veterinary Medicine, University of Mosul, Mosul, Iraq).

3.7. Diagnostic and Therapeutic Approaches

Most functional ovarian disorders are clinical problems and can be diagnosed by clinical methods such as transrectal palpation and transrectal ultrasonography. Transrectal palpation or transrectal ultrasonography in silent estrus buffaloes on the day of estrus reveals a normal sized ovulatory follicle and tonicity in the uterus [26,136]. When making a diagnosis, one must consider that in many cases, the first and second postpartum ovulations are quiet ovulations that oftentimes stock keepers overlook external estrus signs [137] and adequate diagnostic measures must be taken to rule out a retained corpus luteum or pregnancy.

Transrectal ultrasonography is more precise in evaluating ovarian follicles and confirming ovulation [29,37]. The evaluation of the development and demise of the corpus luteum can be performed by transrectal ultrasonography and validated by measuring progesterone [27,29,31]. The diagnosis of a persistent CL is based on its presence for more than 24 days, whether uterine pathology is present or not. Thus repeated examinations are suggested at weekly intervals. It is appropriate to evaluate the blood progesterone profiles at similar intervals to confirm the presence of luteal tissue. Ovulation can be detected by the repeated examination of an ovulatory sized follicle. Follicular ovarian cysts can be diagnosed based on their size (Fig. 8) and persistence of large fluid filled structures (Fig. 9) by transrectal palpation or transrectal ultrasonography (Fig. 10). Luteal cysts appear as hard structures projecting on the ovarian surface (Fig. 11) although they are sometimes embedded in the ovarian stroma (Fig. 12). The diagnosis of luteal cysts requires concomitant evaluation of plasma progesterone profiles which continue to be elevated. It is clinically difficult to differentiate luteal cysts from normal corpora lutea. Paraovarian cysts can be diagnosed accidentally during transrectal palpation; however, this can only be done when their size is greater than 1.0 cm.

Figure 8. A follicular cyst in a buffalo ovary. A) Right ovary. B) Left ovary (Photo Courtesy Prof. Azawi O.I., Department of Surgery and Theriogenology, College of Veterinary Medicine, University of Mosul, Mosul, Iraq).

Figure 9. Cut surface of fluid filled follicular cysts on buffalo ovaries.

Figure 10. Transrectal ultrasonogram showing an anechogenic follicular cyst (23.0 mm) on a buffalo ovary.

Figure 11. Luteal cyst on the right ovary of a buffalo (Photo Courtesy Prof. Azawi O.I., Department of Surgery and Theriogenology, College of Veterinary Medicine, University of Mosul, Mosul, Iraq).

Figure 12. Cut surface of a luteal ovarian cyst on a buffalo ovary. The gross section revealed only a discolored center and the condition was confirmed to be a luteal cyst on histopathology.

The therapy for most functional ovarian disorders is similar to that described for cattle [89] and includes prostaglandins for subestrus [138] and persistent CL [3], mineral, vitamin or hormonal supplementation for ovarian inactivity [136,137,139-143], and GnRH and hCG for ovulatory disorders such as ovarian cysts [95,144]. The therapy of paraovarian cysts is neither possible nor required in small cysts.

4. Ovarian Neoplasms and Associated Conditions

4.1. Ovarian Tumors

Ovarian tumors have been described in the buffalo mostly from studies on abattoir specimens [13,14,77,82,93,94,145-147]. Only one study on 2570 buffaloes in India described the incidence of tumors as 0.11% [134].
Classification of ovarian tumors assumes that these tumors arise from one of the three ovarian compartments: epithelium; germ cells, or ovarian stroma, including the sex chords [43].

Epithelial Tumors

Epithelial tumors are uncommon in most domestic animals including the buffalo. The vast majority of epithelial tumors arise from the surface epithelium, and rarely from the rete ovarii [43]. Epithelial tumors of the ovary are usually cystic and papillary, thus the names cystadenoma and cystadenocarcinoma are frequently used. Histologic descriptions mention that such tumors consist of arboriform papillae that project into the cyst lumen [43]. A few studies on abattoir specimens in buffalo recorded cystadenoma [77,82,147], however, clinical descriptions of such tumors are not available.

Germ Cell Tumors

Germ cell tumors are composed of a number of histologically different tumor types derived from the primitive germ cells of the embryonic gonad [148]. The concept of germ cell tumors is based on

i) The common histogenesis of these neoplasms,
ii) The relatively frequent presence of histologically different neoplastic elements within the same tumor mass and
iii) The presence of histologically similar neoplasm in extra gonadal locations [148].

In the buffalo species many reports described the germ cell tumor teratoma [5,13,19,77,82,93,94,145-147], and dermoids [14,82]. Both dermoids and teratoma are considered benign. Dermoids are also known as mature teratoma. Dermoids are cysts (1.25-6.25 cm) within the ovary with sebaceous glands and hair follicles. On excision, clusters of hair and other tissues are found [14]. The incidence of dermoids was only 0.4% in 3684 buffalo genitals examined [14] and 1.44% for 1725 abattoir derived genitals examined [82]. The incidence of dermoids in buffaloes in Karnataka (India) was 1.0% [51] and in a recent study it was 0.71% [81]. The etiology of germ cell tumors is poorly understood.

Sex Cord–Stromal Tumors

Sex cord stromal tumors are derived from, or histologically resemble, the normal cellular constituents of the ovary other than the epithelium or germ cells [43]. Ovarian sex cord stromal tumors are a heterogeneous group of benign or malignant tumors that develop from the dividing cell population that would normally produce cells which support and surround the oocytes, including the cells that produce ovarian hormones [149] and include granulosa cell tumors, granulosa-theca cell tumors. Folliculoids are granulosa cell tumors in variegated forms (appearance of differently colored zones) with a tendency of these cells to arrange in small clusters as seen in histopathologic sections (Fig. 13).

The most common ovarian sex cord stromal tumor in the buffalo appears to be granulosa cell tumor [82,150]. The incidence of such a tumor in buffaloes was 0.71% in a recent study [81]. Folliculoids have also been recorded in the buffalo. For 600 abattoir derived buffalo genitalia studied, 25 (4.16%) contained folliculoids (13 unilateral and 12 bilateral). It was mentioned that folliculoids are probably anovulatory follicles of aged buffaloes that persist and proliferate under the constant stimulus of gonadotrophins [150]. The incidence of trabecular (Fig. 14), microfollicular (Fig. 15) and pseudoadenomatous folliculoids was 36.0%, 44.0% and 20.0% respectively [150]. In a recent study, the incidence of folliculoids was 0.24% [81]. Endocrine abnormalities have been associated with sex cord stromal tumors [43] although this has not been documented in buffaloes.

Figure 13. Microphotograph of an ovary showing an anovular cord. Note the arrangement of granulosa-like cells and the homogeneous material in the center. H&E 200X.

Figure 14. Microphotograph of a buffalo ovary showing trabecular folliculoids with a well-delineated capsule projecting invagination into the lumen. H&E 200X.

Figure 15. Microphotograph of a buffalo ovary with colloid type folliculoids with irregular PAS-positive colloid bodies (darker structures) in the lumen. Periodic Acid Schiff 100X.

Mesenchymal Tumors

Mesenchymal tumors comprise a heterogeneous group of neoplasms that are not specific to the ovary [151] and include fibromas, hemangiomas, leiomyomas, and their malignant counterparts [43].

In buffaloes, only hemangioma has been described [77]. Luktuke et al. [152] observed proliferative or lymphosarcomatous growths in anestrus ovaries of buffaloes and a fibroma was recorded in buffalo ovaries in a recent study [19].

4.2. Hematoma

A vascular hematoma is a non-neoplastic malformation that is present at birth and grows until puberty [153]. Hematoma in the ovaries of Indian buffaloes were reported previously [12-14,77,78,82]. The incidence ranged from 0.26% to 1.43%.

4.3. Diagnostic and Therapeutic Approaches

Most bubaline ovarian tumors produce few clinical signs. The loss of reproductive function in ovarian tumor affected buffaloes subsequent to bilateral removal of the ovaries renders any treatment limited because of economic considerations. Plasma anti-Müllerian hormone was tested as a biomarker for detection of bovine granulosa-theca cell tumors in a recent study [154] with high accuracy; however, the clinical application of such a test is limited.