Clinical history

A 2-year-old female ostrich (Struthio camelus) was examined to assess a weight loss of several months’ duration.

The bird was housed in a large outdoor grassed pen with another hen and a cock. The farm was in a high-rainfall coastal area on sandy soil, and held over 300 birds in numerous pens. The birds were fed a daily diet of a commercial ostrich maintenance pellet and grain. Water was supplied via polypropylene pipes. There were several dams on the property, attracting large numbers of ibis and egrets to the farm.

The bird had been purchased 18 months previously but had not yet bred. Its appetite was poor.

Clinical examination

On presentation, the bird was weak and in very poor body condition, with a prominent spine and pelvic bones. There was no evidence of dyspnoea or increased respiratory effort. Skin tone was reduced and urine production was scant. The bird’s faeces were small and pelletized. Abdominal palpation and auscultation of the cardiorespiratory system were normal. Cloacal examination revealed multiple nodules on the cloacal mucosa.

Blood was collected for haematology and biochemistry analysis, and a cloacal mucosal nodule was biopsied. Faeces were collected for parasitological examination.

Clinical diagnosis laboratory

The results of the clinical diagnosis laboratory assays are shown in Tables 2.1 and 2.2.

Table 2.1 Haematology values of the ostrich

Table 2.2 Blood chemistry values of the ostrich

Results

Please evaluate the clinical history, the results of the physical examination and clinical diagnosis laboratory tests.

2. List your differential diagnoses.

Differential diagnoses

Outcome

A presumptive diagnosis of avian mycobacteriosis was made. In light of the bird’s physical condition and clinical pathology findings, the owner opted for euthanasia.

Post-mortem findings

The cloacal nodule biopsy revealed a granulomatous reaction associated with numerous acid-fast bacilli. A thorough post-mortem examination was performed. Samples from different organs were collected for histopathology, culture and polymerase chain reaction (PCR).

On necropsy, the bird was emaciated with bright yellow subcutaneous and internal body fat. The liver was enlarged with multifocal, densely packed, small white nodules (>5 mm in diameter) on the surface and throughout the parenchyma (Fig. 2.1a, b). Similar nodules of various sizes (2–35 mm) were scattered over the serosa and mucosa of the intestinal tract, protruding into the lumen. Both caecae were covered with a yellow fissured membrane and the lumen contained a clear gelatinous material in which some flocculent material was suspended.

Fig. 2.1 (a) Post-mortem examination of the ostrich showing necrotic foci in the liver (courtesy of Kaye and Marcus Holdsworth); (b) section of the liver showing small and large necrotic foci on the surface and throughout the parenchyma of the liver

(courtesy of Kaye and Marcus Holdsworth).

The heart, lungs, air sacs, kidneys and spleen appeared normal.

Summary of post-mortem examination findings

3. What is your provisional post-mortem diagnosis?

Provisional post-mortem diagnosis

Laboratory findings

Final diagnosis

4. What advice would you give the owner of this bird regarding the infectious and zoonotic potential of this disease?

Discussion

Avian mycobacteriosis is an uncommonly reported disease of ratites, although reports in other avian species are widespread.

M. avium is an opportunistic pathogen in birds and mammals, including humans. It can cause disease in most, if not all, avian species and is characterized by its chronic nature, its persistence in a flock once established, and its tendency to cause wasting and finally death. It can be found in soil, feed and water, particularly where faecal contamination by infected birds can occur, and it can persist in soil for several years. On an ostrich farm, contamination of soil and water could be expected to be due to infected ostriches or wild birds, or by mechanical transmission on clothing, vehicles and equipment.

Infection is believed to be due to ingestion and, as ostriches are noted for their soil-eating behaviour, it is likely that this was the source of infection in this case. The disease is primarily gastrointestinal in presentation; lymphatic drainage of the gastrointestinal tract then spreads the infection to other organs in the body, especially the liver.

Although M. avium can be associated with disease in humans – an Australian study showed that, between mid-1985 and late 1988, 17.3% of people with AIDS had concomitant M. avium infections – birds are not thought to be the direct source of infection. Rather, it is the contamination of food and water that is thought to lead to human infection. Nevertheless, the zoonotic potential of this disease is present and owners of infected birds should be advised of this.

In the poultry industry, avian mycobacteriosis is not considered to be a major production threat because of the early slaughter age for chickens. In ostriches, however, where the slaughter age is much older (8–12 months), it is possible that mycobacterial infection in a flock could pose a threat to production.

Ante-mortem diagnosis of avian mycobacteriosis is difficult. Intradermal tuberculin sensitivity testing is not considered reliable in an individual bird and, in fact, a strong response could indicate a highly resistant bird rather than an infected bird. The potential use of intradermal testing may be to determine if a flock, rather than an individual, is infected with mycobacteria. Its use in ostriches has yet to be fully evaluated.

Clinical history

An adult female African fish eagle (Haliaeetus vocifer) weighing 1800 g, was presented with the following clinical signs of three days’ duration:

The bird had recently been imported from Africa into Dubai as a display bird for a falconry show, but was not being trained.

Clinical examination

On presentation, the bird was thin with marked loss of pectoral muscle condition and pale mucous membranes. Parasitology crop swabs for wet preparation and faecal samples for direct smear and flotation were performed. Survey radiographs were taken while the bird was under anaesthesia (Fig. 2.2a, b). Blood samples were collected for haematology analysis. Endoscopy examination of the caudal thoracic air sacs and upper digestive tract and trachea was also performed.

Fig. 2.2 (a) Ventrodorsal survey radiograph of the African fish eagle; (b) lateral survey radiograph of the African fish eagle.

Endoscopy

Endoscopy examination of the upper gastrointestinal tract and trachea revealed no abnormal findings. Endoscopy of the caudal thoracic air sacs was conducted (Fig. 2.3). A swab was collected from the caudal thoracic air sacs and submitted for microbiological and cytology investigations (Fig. 2.4).

Fig. 2.3 Endoscopic view inside the caudal thoracic air sac of the African fish eagle.

Fig. 2.4 Photomicrograph of cytology preparation from a swab of the caudal thoracic air sacs of the African fish eagle. Note the smear was negative for acid-fast bodies.

Clinical diagnosis laboratory

The results of the clinical diagnosis laboratory assays are shown in Table 2.3 and the blood film in Fig. 2.5.

Table 2.3 Haematology values of the African fish eagle

* ISIS values are for African fish eagles (n 2–11).

Fig. 2.5 Photomicrograph of blood film from the African fish eagle.

4. What is your interpretation of the haematology values shown in Table 2.3? What is your interpretation of the blood film in Fig. 2.5?

Other laboratory results

Please evaluate the clinical history, Figs 2.2–2.5, the results of the radiography and endoscopic examinations and clinical diagnosis laboratory tests.

5. List your final diagnosis.

Clearly, there are two pathological processes contributing to the morbidity of this bird.

6. List your therapeutic strategy.

Therapy

Treatment for malaria comprises giving chloroquine at a dose of 25 mg/kg PO and 1.3 mg/kg primaquine PO initially. Twelve hours after the initial combination, 15 mg/kg chloroquine is given and 24 hours after the initial combination dose 15 mg/kg PO of chloroquine is repeated; 48 hours after the initial combination dose the final 15 mg/kg chloroquine is given.

The profound anaemia of this bird should also be addressed. Homologous blood transfusions have been shown to be beneficial for birds with severe anaemia (PCV <20%) and are feasible where there is a donor bird of the same species available. The haemoglobin-based oxygen carrier, Oxyglobin (Biopure, USA) is becoming more widely used in avian medicine. This product is indicated during resuscitation when increased oxygen delivery to the tissues is desired. Intravenous colloids with replacement fluids (isotonic crystalloids) are indicated if neither Oxyglobin nor a homologous blood transfusion are possible.

If the disease is diagnosed in the early stages, aspergillosis can be successfully treated with oral itraconazole or voriconazole and nebulization with amphotericin B or F10 (Table 2.4). One caution in such a profoundly anaemic bird would be to deal with the malaria first because sometimes the azole antifungal agents can cause anorexia, particularly in debilitated birds.

Table 2.4 Dosage protocols of some antifungal agents in birds

Supportive therapy including fluids (IV, SC, IO), tube feeding, antibiotics, antiemetic drugs, immune stimulants and vitamin A supplementation should be given according to the needs of the case. Vitamin B complex and iron injection are both recommended initially for anaemic birds.

Discussion

One criticism of the workup in this case was the diagnostic workup that involved a lengthy anaesthesia to enable radiography and endoscopy examinations. However, in this case, the radiographic findings resulted in the endoscopy investigation to establish the cause of the radiographic lesions. The blood findings were only apparent some hours later when the results were released from the laboratory.

In general, the pathogenicity of blood parasites in most birds of prey is relatively low, but Plasmodium spp. has been linked with deaths in gyr falcons and snowy owls.

Plasmodium spp. use mosquitoes as vectors. Plasmodium spp. has been reported in free-living African fish eagles in Africa. In a dual aspergillosis–malaria infection such as this case, it is possible that the bird developed aspergillosis as a result of the stress of being shipped between countries and may have precipitated the recrudescence of the Plasmodium infection.

One important consideration hampers the diagnostic procedure for malaria. Stress resulting from manual restraint to collect blood samples has caused death in gyr falcons with malaria. Isoflurane anaesthesia of the patient to minimize stress before diagnostic sampling and treatment is recommended.

In countries where there is a high prevalence of malaria, prevention is important. Prevention is based on two approaches. First, vector exclusion through mosquito control and prophylactic treatment. Prophylactic treatment consists of a once weekly single treatment with chloroquine–primaquine combination commencing 1 month before and finishing 1 month after the mosquito season.

Prophylactic itraconazole is recommended for captive-held birds undergoing a change in management to reduce the chances of mycotic pneumonia occurring, especially high risk species and during times of stress such as transportation between countries.

Clinical history

A 15-year-old female Harris’ hawk (Parabuteo unicinctus) weighing 910 g was presented as a referral with thickening and ulceration of the skin on the neck. The bird was reportedly irritated by the lesion. The referring veterinarian had not performed any diagnostics. However, the bird had not responded to two courses of antibiosis (enrofloxacin) or to topical fusidic acid, but had responded to a fusidic acid/corticosteroid topical gel preparation. During this time the lesion had regressed partially. However, when the gel was discontinued, the lesion returned. At the time of examination the bird had been on no therapy for 2 weeks.

Physical examination

The bird was in good body condition. No abnormality was detected other than a large ulcerated, thickened skin lesion of the ventral neck (Figs 2.6 and 2.7).

Fig. 2.6 Ventral view of the neck of the Harris’ hawk clearly showing the lesion.

Fig. 2.7 Close-up view of the lesion on the ventral neck.

1. What are your differential diagnoses?

The bird was anaesthetized using isoflurane.

2. What clinical investigations would you perform?

Clinical diagnosis examination

Endoscopy examination was carried out of the upper gastrointestinal tract.

Clinical diagnosis laboratory examination

Blood samples were collected for haematology, blood chemistry and protein electrophoresis (Fig. 2.8) analyses (Tables 2.5–2.7). In addition, cytology smears, skin biopsies and bacteriology swabs were collected from the lesion.

Fig. 2.8 Plasma protein electrophoresis graph in the Harris’ hawk.

Table 2.5 Results of the biochemistry analyses in the Harris’ hawk

Table 2.6 Results of the haematology analyses in the Harris’ hawk

Table 2.7 Results of the plasma protein electrophoresis analysis in the Harris’ hawk

Summary of diagnostic results

3. What is your interpretation of the blood analyses?

The albumen:globulin (A:G) ratio suggests inflammatory disease and this is borne out by the electrophoresis. A prominent alpha 2 fraction suggests an acute phase inflammatory reaction while a polyclonal gammopathy indicates a chronic component. Otherwise there are no significant findings.

4. What do you think of the significance of the bacterial isolate?

This was clearly a contaminant or opportunistic invader. Had it been a primary cause there would have been a more significant response to previous antibiosis.

Histopathology confirmed the presence of squamous cell carcinoma with a secondary bacterial pyoderma.

Final diagnosis

5. What will be your course of action?

Squamous cell carcinoma is common in older Harris’ hawks. While radical excision and phototherapy may be appropriate in some cases, this was clearly not possible in this situation. Given the previous beneficial response to topical corticosteroid/fusidic acid gel, it was decided to resume using this. While topical corticosteroids are normally contraindicated, this case had a hopeless prognosis so therapy was deemed palliative at best. Euthanasia was offered but declined by the owner at that time as the bird appeared well. The bird did well on topical therapy for over six months before euthanasia.

Clinical history

A 13-year-old female Harris’ hawk (Parabuteo unicinctus) was presented for examination. The bird had only been in the owner’s possession for 2 years, but there was no history of ever having previously been bred from. The owner ran a falconry experience company and took clients out flying with his birds. However, he was unable to fly this bird with guests as it was aggressive towards all humans except the falconer himself. In the past month, the bird had been increasingly vocal and had built a nest in her aviary. The falconer had observed that the bird had laid an egg 3 days previously and now had a red soft tissue structure protruding from her vent.

Clinical history summary

Physical examination

On examination, the hawk was found to be in good body condition, with a well-developed ventral brood patch and a cloacal prolapse as shown in Fig. 2.9.

Fig. 2.9 Cloacal prolapse in the Harris’ hawk. The bird had laid an egg 3 days previously.

Clinical diagnosis examination

1. What are the structures which could be found prolapsed from a cloaca of a female bird?

2. What are the possible causes of cloacal prolapse?

3. What structure is prolapsed in this case?

4. What tests should be performed to elicit the cause of prolapse in this case?

A1. Cloaca, oviduct, colon.

A2. Any cause of tenesmus (e.g. oviductitis, egg peritonitis, cloacitis, cloacolith, hypersexuality resulting in masturbation and physical trauma, egg laying-related trauma, trauma subsequent to mating or artificial insemination, bacterial, yeast or parasitic enteritis, gut or oviduct obstruction), relaxed cloacal sphincter (typically secondary to egg laying or hypersexuality) with secondary cloacal exposure or trauma.

A3. Cloaca.

A4. Cloacal cytology, faecal cytology for parasites or infection, radiography and coelioscopy (endoscopic visualization of internal viscera), clinical examination of the cloaca and cloacal sphincter.

Summary of diagnosis results

5. List your differential diagnoses.

6. List your therapeutic strategy.

Differential diagnoses

Therapy

Response to therapy

Discussion

This problem appears to have arisen due to an inappropriate desired breeding relationship between the bird and the keeper. The same desired relationship is also likely to be the cause of the bird’s aggression towards other humans when out flying. Both repeated attempted breeding and territorial or mate, hormonally-derived behaviour can be effectively controlled by the subcutaneous insertion of a gonadotrophin-releasing (GnRH) implant (Suprelorin, Virbac Animal Health). This bird received an implant one week after the prolapse episode. She did not attempt to lay eggs again over the subsequent 12 months and became a friendly bird capable of being flown with guests. Implants remain efficacious for approximately 12 months in birds.

Clinical history

During a standard consultation at a breeding facility with a mixed psittacine and birds of prey population, a 5-year-old male snowy owl (Bubo{Nyctea} scandiacus) was presented with the following clinical signs of several weeks:

The bird was housed in a breeding aviary measuring around 4×4 m and 2.5 m height. The owner reported that the bird had been involved in an accident a few months before when he accidentally lost his balance, and to avoid falling down, he put all his weight on the bird’s back. He suspected he damaged the bird’s spine and that as a consequence, the bird could not fly since then.

Clinical diagnosis examination

On presentation, the bird had a reduced body condition of 2/5. Survey radiographs were taken while the bird was under anaesthesia (Fig. 2.10a, b).

Fig. 2.10 (a) Ventrodorsal survey radiograph of a 5-year-old male snowy owl; (b) lateral survey radiograph of the snowy owl.

Clinical diagnosis laboratory examination

Blood samples were collected for haematology, but the client declined blood chemistry. The results of the haematology analysis are shown in Table 2.8.

Table 2.8 Haematology values of the snowy owl

Film comments

Moderate leucocytosis

Heterophilia

Heterophil toxicity

2. What is your interpretation of the haematology values shown in Table 2.8?

After having explained the results, the owner agreed to a coelioscopy, to investigate the abdominal radiodense masses as observed in the survey radiographs (Fig. 2.11a, b).

Fig. 2.11 (a,b) Endoscopic view of the coelomic cavity of the snowy owl.

The endoscopy examination showed disseminated whitish masses within the coelomic cavity. During the procedure samples were taken for cytology and microbiology.

Summary of clinical diagnosis laboratory results

Please evaluate the clinical history, Figs 2.10a, b, 2.11a, b, the results of the physical examination and clinical diagnosis laboratory tests.

3. List your differential diagnoses.

4. List your therapeutic strategy.

Differential diagnoses

Therapy (Table 2.9)

Unfortunately, after 2 days of treatment and no obvious improvement, the owner opted for euthanasia.

Table 2.9 Therapy

Post-mortem findings

A thorough post-mortem examination was performed (Fig. 2.12a–d). Samples from different organs were collected for histopathology.

Fig. 2.12 (a–d) Post-mortem photographs of the snowy owl.

5. What lesions can you observe in the post-mortem photographs?

6. What is your provisional post-mortem diagnosis?

Summary of post-mortem examination findings

During the examination, it was suspected that the pathology had started from the kidney region. The kidneys could not be located and had been “replaced” by a large whitish mass.

Provisional post-mortem diagnosis

Laboratory findings

Final diagnosis

Discussion

The owner suspected trauma as the cause of the bird’s inability to fly. Radiographs revealed the presence of disseminated masses that could not be related to trauma. Haematology pointed to a possible infection (leucocytosis, heterophilia and heterophil toxicity), but this was not supported by the microbiology samples collected during endoscopy. The endoscopy examination showed several small masses filling almost every space of the air sacs. This was a very unusual endoscopy finding. The bird was euthanased as there was little that could have been done to save the bird. This became obvious at post-mortem examination. The perception of the owners could very often lead to a wrong diagnosis, but a professional approach to the case often leads, if not to save a bird, at least to provide a definite diagnosis. Unfortunately, it was not possible to carry out histopathology examination. The most important aspect of the case for the owner was that the bird was not undergoing an infectious process that could have threatened the rest of the birds in the breeding facility.

Clinical history

A 6-month-old female gyr falcon (Falco rusticolus) was presented for examination. The captive-bred bird was used in the sport of falconry and it was in the early stages of training. One afternoon the falcon owner noticed the falcon drooling saliva and repeatedly making a clacking noise after feeding. He inspected the oro-pharynx and palpated the neck thinking of a bone caught at the entrance of the crop, but could not find anything abnormal. The following day, the falcon was normal so he ignored the symptoms observed the previous day. Two days later, the bird began passing green-coloured urates and did not look well, therefore he decided to take it to a veterinarian for consultation. The falcon was presented for examination with the following clinical signs observed in the past 2 days:

Physical examination

On examination, the falcon was found relatively alert and responsive. The bodyweight was 1156 g with a body condition of 3/5 and was mildly dehydrated. The bird was weak and had to be assisted back to the glove after a failed attempt to carry out an endurance test.

Clinical diagnosis examination

Survey radiographs were taken while the bird was under anaesthesia (Fig. 2.13a, b). Endoscopy examination of the upper digestive tract and trachea was also performed.

Fig. 2.13 (a) Ventrodorsal survey radiograph of a 6-month-old female gyr falcon; (b) lateral survey radiograph of the gyr falcon.

Clinical diagnosis laboratory examination

Blood samples were collected for haematology, blood chemistry and plasma protein electrophoresis analyses. A faecal sample was collected to examine for the presence of endoparasites.

The results of the clinical diagnosis laboratory assays are shown in Tables 2.10–2.12.

Table 2.10 Haematology values of the gyr falcon

Table 2.11 Blood chemistry values of the gyr falcon

Table 2.12 Plasma protein electrophoresis of the gyr falcon

Summary of diagnostic results

Please evaluate the clinical history, Fig. 2.13a, b, the results of the physical examination and clinical and laboratory diagnostic tests.

4. List your differential diagnoses.

5. List your therapeutic strategy.

Differential diagnoses

Therapy

The falcon was placed on the therapeutic management shown in Table 2.13.

Table 2.13 Therapy

Post-mortem examination

The falcon continued deteriorating despite support therapy and died on the fourth day of admission. A thorough post-mortem examination was performed (Fig. 2.14). Samples from different organs were collected for microbiology, histopathology and virus isolation.

Fig. 2.14 Post-mortem photograph of the gyr falcon.

6. What lesions can you observe in the post-mortem photograph?

7. What is your provisional post-mortem diagnosis?

Summary of post-mortem examination findings

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